rosco
11-21-2006, 04:41 PM
Several years ago I had lots of HVAC problems related to dramatically oversized equipment. One of the side effects of this oversized equipment was the inability to humidify using simple furnace humidifiers due to short runtimes. Many in this forum helped me understand what was going on, and we are now starting our second heating system with the new system. The new system uses a condensing boiler with outdoor reset - temp vary from 100F to 145F in the heating curve so we are always condensing feeding two variable speed hydro-air handlers. A indirect DHW tank was installed as well.
With the exception of one relatively minor issue (balancing the air through the new attic ducts) everything is working like a dream. We went from short on/off bang bang type operation to smooth ultra-long runtimes at very low air velocities. The air coming out of the ducts is warm and nearly silent even with the relatively low boiler temps. The ultra-long runtimes has also allowed a standard flow-through humidifier to do such a great job that I have to keep it from running too much. The humidifier is a Skuttle 2001 setup with the optional second air intake. The Skuttle person on this forum was always very good about answering questions, so I asked my contractor if he would consider putting in this unit. I can't say enough good things about the performance of this unit.
Many thanks to all who answered my questions.
PS - The one remaining problem is a bit of a mystery. The contractor who did the work came up with a very good redesign of the attic duct work. Off the air handler the ducts branch into two sections with an unequal number of vents on each. They are round insulated steel rigid ducts with short flex duct sections attaching the main trunks to the vents. I saw them use the duct calculator to size everything and it all makes sense. In spite of all this, one branch seems to get more than it's share of the flow. I need to call this contractor back and get him to figure out the problem (although he was talking about moving to a warmer climate).
With the exception of one relatively minor issue (balancing the air through the new attic ducts) everything is working like a dream. We went from short on/off bang bang type operation to smooth ultra-long runtimes at very low air velocities. The air coming out of the ducts is warm and nearly silent even with the relatively low boiler temps. The ultra-long runtimes has also allowed a standard flow-through humidifier to do such a great job that I have to keep it from running too much. The humidifier is a Skuttle 2001 setup with the optional second air intake. The Skuttle person on this forum was always very good about answering questions, so I asked my contractor if he would consider putting in this unit. I can't say enough good things about the performance of this unit.
Many thanks to all who answered my questions.
PS - The one remaining problem is a bit of a mystery. The contractor who did the work came up with a very good redesign of the attic duct work. Off the air handler the ducts branch into two sections with an unequal number of vents on each. They are round insulated steel rigid ducts with short flex duct sections attaching the main trunks to the vents. I saw them use the duct calculator to size everything and it all makes sense. In spite of all this, one branch seems to get more than it's share of the flow. I need to call this contractor back and get him to figure out the problem (although he was talking about moving to a warmer climate).